Saturday, January 25, 2014

In 1811 and 1812, it unleashed a trio of powerful jolts —measuring magnitudes 7.5 to 7.7 —that rattled the central Mississippi River valley. Chimneys fell and boats capsized. Farmland sank and turned into swamps. The death toll is unknown, but experts don't believe there were mass casualties because the region was sparsely populated then.

"Our new results tell us that something is going on there, and therefore a repeat of the 1811-1812 sequence is possible," Hough said.

The USGS estimates there's a 7 to 10 percent chance of that happening in the next 50 years.